Furnace



Jan. 18, 1938. R. M. PARSONS FURNAC E lFilec Aug. 20, 1936 5 Sheets-Sheet 1 .I 74 www INVENTOR `/a//f/n faisons BY I I/v. l f

RNEY

Jan. 18, 1938. R. M. PARSONS 2,105,821

FURNACE Filed Aug. 42O, V1936 3 Sheets-Sheet 2 IR 7m Jan. 1s, 193s. R. M. PARSONS 2,105,821

FRNACE Filed Aug. 20, 1936 3 Sheets-Sheet 3 INVENTOR Fal/4h fravm ORNEY Patented Jan. 18, i938 unirse srArE-s FUBNAUE' Ralph M. rai-sons, chicago, nl., assignor fo The Ralph M. Parsons Company, Chicago,

Ill., a

corporation of Delaware Application August 20, 1936, Serial No. 96,939

10 Claims.

This invention relates to furnaces and more particularly `to tube stills for use in oil cracking and rening plants.

In one embodiment, the invention is applied to a furnace having a vertically elongated cornbustion chamber'containing a bank of radiant heat-tubes and a convection chamber disposed above the combustion vchamber in alignment therewith. The burners are located at the bottom of the combustion chamber so that the combustion gases are caused to pass upwardly over the various tubes in the combustion and convection chambers and are withdrawn from the top of the convection chamber.

10 An object of the present invention is to provide an improved means for mounting and supporting the tubes in the combustion and convection chambersof a furnace of the above type.

Another object is to improve the details of construction and method of operation of such a furnace. I

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed. Y

A feature of the invention consists in the provision of a supporting frame located outside of the furnace walls and carrying trusses which support the various tubes. Both the convection tubes and the radiant heat tubes are carried in tube sheets which are hung from the above mentioned trusses. The radiant tube sheets are suspended below the convection tube sheets and extend vertically down the center of the combustion chamber to support the radiant heat tubes in a position to receive radiant heat from both of the furnace walls. y

Various other features consist in the details of construction and combination of parts, hereinafter more fully set forth.

Although the invention is capable of various uses, it will be understood from the following description and the accompanying drawings, in which one embodiment thereof is set forth for purposes of illustration.

In the drawings:

Fig. 1 is a vertical, longitudinal section through a furnace embodying the present invention;

Fig. 2 is a transverse section taken along the line 2-2 of Fig. 1;

Fig. 3 is 'a transverse section of the furnace taken along the line 3-3 of Fig. l; y v

Fig. 4 is a partial section taken along line d-I of Fig. l showing details of the anchor for the end tube sheets;

Fig. 5 is a section taken along the line 5.5 of Fig. 4; and

Fig. 6 is a perspective showing the arrangement of the supporting truss and the means for suspending the tube sheets therefrom.

Referring to the drawings more in detail, the

(Cl. 122-356) i invention a's shown is applied to a furnace having a combustion chamber I0 provided with side walls I I and end walls I2, and a convection chamber I3 of smaller cross section than the combustion chamber Il) located directly thereover. The convection chamber I3 is provided with side walls Id which may be joined to the side walls II 'by sloping sections I6. A hood I'I is mounted above the convection chamber I3 and is adapted to conduct the exhaust gases to a stack I8. The walls II and I2 may be supported upon side and end foundations 2l and 22, respectively. A oor 23 may be supported by a plurality of transverse beams 2d resting upon the side foundations 2| and central piers 25. Between the side foundations 2! and the central piers 25, rows of burners 26 and 27 are provided, which are inclined toward the side walls so as to direct the ame against said walls for heating' the same to radiance. The burners 26 may be provided with a ared central passage 28 through which gaseous fuel and air for combustion are passed. The burners 2l may have a similar central passage 29 formed therein which communicates with a jet 30 supplied with liquid fuel and air or steam for atomizing from pipes 3l. Air for combustion is supplied to the passages 29 from ducts 32, which receive the air from ducts (not shown) extending upwardly along the side walls of the furnace. and terminating at the top of the side walls. It is to be understood that the burners 2S and 2l may be used alternately depending upon whether liquid or gaseous fuel is to be employed.

The lower part`- of the side walls II, against which the ame from the burners is directed, muy be thicker than the upper part of said walls which are not required to withstand the same intensity of heat and are not relied upon to absorb the radiant heat and to re-radiate the same to the radiant heat tubes, to be described. The side walls It of the convection chamber I 3 may be of still thinner construction as they are subjected only to convection heat. The walls may have an outer covering 35 of impervious material, such as sheet rockor any material which will prevent escape of air' or combustion gases. If desired, the walls may be made of monolithic refractory cement in which case they are substantially air and gas tight and the outer lining may not be required.

For supporting the walls Ill and I 6, and the various tube sheets to be described, there is provided a framework comprising side buck stays 36 and end buck stays 31 which may rest upon the foundations 2l and 22, respectively. The side walls II may be anchored to the side buck stays 36 at convenient points' by suitable means not shown.

A set of vertical truss members 40' and inclined truss 'members 4I are positioned adjacent the side walls i4 and the sloping walls IG of the furnace. Suitable means, not shown, may be provided to secure the walls to these truss members. The vertical truss members 40 form a part of a vertical truss comprising a top plate 42, bottom plate 43 and bracing members 44. The tops of the buck stays 36 are joined by the cross members 45 to the top plate 42 to form an upper horizontal truss. The upper ends of the inclined members 4| are joined to the side buck stays 36 by horizontal members 46. Longitudinal member 41 joining the side buck stays 36 at the point of attachment of the horizontal members 46 forms, in conjunction therewith, a lower horizontal truss. The various truss members are preferably joined together by welding to form a rigid structure.

End and intermediate convection tube sheets 50, and 50a, respectively, are provided carrying convection tubes 5I and located in the convection chamber I3. These convection tube sheets 50, 56a are provided with hangers 52, 52a, respectively, which extend over and seat in channels 53 carried by a longitudinal plate 54 secured to the top plate 42.

The lower convection tubes 58 in the convection chamber are carried by end and intermediate lower tube sheets 59 and 59a, respectively, which are provided with hangers 60 and 60a, respectively, extending through the walls I4 and resting between gussets 6| on the ends of the horizontal members 46 and on the bottom plate 43. Lugs 6 la are formed on the hangers 60 and 60a to engage the ends of the horizontal members 4B for positioning the hangers. The intermediate lower tube sheets 59a carry suspended radiant tube sheets 62 which are formed with brackets 63 projecting alternately on opposite sides of the tube sheets 62 so as to support the two rows of radiant heat tubes 64 in staggered relationship. The end tube sheets 59 carry end radiant tube sheets 65 which are provided with apertures 66 in which the radiant heat tubes 64 are mounted.

The end radiant .tube sheets A65 are formed in a plurality of sections which are joined together by links 61. Each section may be provided at its lower end with a flange 68 which engages a yoke 69 carried by an angle iron 10 which extends through the end wall i2 and is supported by the end buck stays 31. The lower ends of the radiant tube sheets 62 and 65 are joined by longitudinal members 12 having forks 13 formed at the ends thereof which are seated over lugs 14 formed on the various tube sheets 62 and 65. The yokes 69 serve to anchor the end tube sheets 65 in position against the end Walls I2 of the furnace, whereas the longitudinal members 12 serve to secure the lower ends of radiant tube sheets 62 and thereby form a comparatively rigid supporting structure for the radiant heat tubes 64. It will be noted that the intermediate radiant tube sheets 62 are also formed in a plurality of sections which are joined together by links 15.

In the above construction, the radiant tube sheets are suspended from the lower tube sheets 59, the latter being hung on the framework of the furnace independently of the upper tube sheets 50. The weight of all of the tubes is accordingly carried by the furnace framework independently of the furnace walls. The independent suspension of the upper and lower tube sheets distributes the weight on the framework and also permits independent removal of the tube sheets for purposes of inspection or repair. The upper tube sheets 5D may be made of cast iron, whereas the lower tube sheets 59, because of the high temperature to which they are subjected,

are preferably made of alloy steel. It is to be understood that suitable heat insulation may be used over the faces of the various tube sheets, if desired.

It will be noted that by suspending the radiant tube sheets from the lower tube sheets 59, all supports at the bottom of the furnace are eliminated and the supply of 'radiant heat from the walls of the furnace to the tubes is unimpeded. In this construction the maximum tube area is utilized for heat transferred and a maximum quantity of heat is thus transferred to the oil without causing overheating or carbonization thereof. Furthermore, a substantial saving of weight is effected since the suspended tube sheets can be made lighter than tube sheets which are supported only at the bottom. The radiant tube sheets extend from a point near the bottom of the combustion chamber to the convection tube sheets, thereby dividing the combustion chamber into two sections and causing the gases from the two rows of burners to pass upwardly on opposite sides of the radiant heat tubes before the gases are allowed to converge into the convection chainber. The tubes 58 carried in the lower tube sheets 59 receive both radiant heat and the heat of convection, whereas the radiant heat tubes84 receive principally radiant heat and the convection tubes 5l receive principally heat of convection.

This furnace is particularly adapted for oil cracking, the arrangement of the tubes being such that high temperatures can be employed and maximum heating eiiiciency obtained. The suspended tube sheets arefree to expand as required, the flanges B8 sliding in the yokes S9 for this purpose. The anchors for the end tube sheets and the members connecting the bottoms of the various tube sheets form a rigid and strong supporting structure for the tubes which is cheap and convenient to install and repair.

It is to be noted that the tubes 58 are arranged in a bank having inclined sides which are di rectly in the path of the combustion gases and are also exposed to the radiant heat from the furnace walls. These tubes protect the convection tubes 5| from the intense radiant heat and, be-

cause of their independent support, can be replaced without disturbing the convection tubes.

The suspended radiant heat tubes are located at the center line of the combustion chamber between the two rows of burners so as to receive heat from both side walls. The burners are inclined toward the side walls to prevent direct impingement of the flame on the above tubes. The location of the burners and the direction of the flame can be varied according to the particular furnace. In some instances, particularly in large furnaces, the burners may direct the flame vertically or somewhat toward the tubes provided the spacing is such as to prevent overheating or burning out of the tubes.

Although a specific embodiment of the invention has been shown for purposes of illustration, it is to be understood that it is adapted to various 'uses and changes and modifications may be made therein without departing from the scope of the invention which is to be limited only in accordance with the following claims when interpreted in view of the prior art.

What I claim is:

l. In a furnace of the class described, side Walls defining a combustion chamber, additional side walls defining a convection chamber located directly above said combustion chamber, a framework located entirely outside of said walls, a

- bank of convection tubes in said convection chamber, tube sheets suspended from said framework and carrying said tubes, a vertical bank of radiant heat tubes located atthe center of said combustion chamber, tube sheets for said radiant heat tubes suspended from said framework independently of said rst tube sheets, and rows of burners on opposite sides of said bank of radiant heat tubes to direct a flame upwardly between said bank and said first side walls.

2. In a furnace of the class described, side walls defining a combustion chamber, additional side walls defining a convection chamber located directly above said combustion chamber, a framework located entirely outside of said walls, a bank of convection tubes in said convection chamber, tube sheets suspended from said framework and carrying said tubes, a vertical bankof radiant heat tubes located at the center of said combustion chamber, radiant tube sheets carrying said radiant heat tubes, hangers associated with said radiant tube sheets, said hangers extending through the side walls and .being supported by said framework independently of said` first tube sheets, and rows of burners onv opposite sides of said bank of radiant heat tubes to direct a ame upwardly between said bank and said iirst side walls.

3.A In a furnace of theclass described, side and end walls forming a vertically elongated combustion chamber, a vertically extending bank of horizontal radiant heat tubes located in the center thereof and dividing the combustion chamber into two sections, burners located in both sections for supplying heat to both sides of said bank of radiant heat tubes, a framework located outside of the furnace walls, hangers extending through said side walls and secured to said framework and tube sheets carried by said hangers to suspend said radiant heat tubes within said combustion chamber.

4. In a furnace of the class described, side and end walls forming a vertically elongated combustion chamber, a vertically extending bank of horizontal radiant heat tubes located in the center thereof and dividing the combustion chamber into two sections, burners located in both sections for supplying heat to both s ides of said bank of radiant heat tubes, a framework located outside of the furnace walls, a row of tube sheets carrying said radiant heat tubes, hangers secured to -said tube sheets, said hangers extending through said side walls and being secured to said framework to suspend said bank of radiant heat tubes within said combustion chamber, and means extending through said end walls to anchor the lower ends of said tube sheets to said framework.

5. In a furnace of the class described, side and end walls forming a vertically elongated combustion chamber, a vertically extending bank' of horizontal radiant heat tubes located in the center thereof and dividing the combustion chamber into two sections, burners located in both sections for supplying heat to both sides of said bank of radiant heat tubes, a framework located outside of the furnace walls, a row of tube sheets carrying said radiant heat tubes, hangers secured to said tube sheets, said hangers extending throughsaid side walls and being secured to said framework to suspend said bank of radiant heat tubes within said combustion chamber, certain of said tube sheets being located adjacent said end walls and means extending through said end walls to anchor the lower ends of said last tube sheets to said framework.

6. In a furnace ofthe class described, side and end walls forming a vertically elongated combus- -tion chamber, a vertically extending bank of horizontal radiant heat tubes located in the center thereof and dividing the combustion chamber into two sections, burners located in both sections for supplying heat to both sides of said bank of radiant heat tubes, a framework located outside of the furnace walls, a row of tube sheets carrying said radiant heat tubes, hangers secured to said tube sheets, said hangers extending through said side walls and being secured to said framework to' suspend said bank of radiant heat tubes within said combustion chamber, certain of said tube sheets being located adjacent said end walls, flanges formed at the lower ends means secured to said framework to slidably engage said anges whereby expansion of said tube sheets is permitted.

7. In a furnace of the class described, side and end walls forming a vertically elongated combustion chamber, a vertically extending bank of horizontal radiant heat tubes located in the center thereof and dividing the combustion chamber into two sections, burners located in both sections for supplying heat to both sides of said bank of radiant heat tubes, a framework located outside of the furnace walls, a row of tube sheets carrying said radiant heat tubes, hangers secured to said tube sheets, said hangers extend,- ing through said side walls and'being secure'd to said framework to suspend said bank of radiant heat tubes within said combustion cham.- ber, certain of said tube sheets being -located adjacent said end walls, said last mentioned tube sheets `comprising a plurality of vertically displaced sections serially joined together and means extending through said end walls to anchor each` section of said framework.

8. A sectional suspended tube sheet comprising a plurality of vertically displaced plates serially joined together, a supporting framework, a hanger attached to the top section to suspend the same from said framework, yokes attached to said framework and vertical anges carried by each section engaging said yokes to anchor the sec- 4tions to said framework.

9. In a furnace of the class described, a cornbustion chamber, a supporting truss on opposite sides thereof, a tube sheet carrying a bank of tubes, hangers on opposite sides of said tube sheetengaging said trusses to suspend the tube sheet therefrom, and an additional tube sheet hung from said first tube sheet and carrying a bank of radiant heat tubes located at the center of said combustion chamber to receive heat equally from both side walls thereof.

10. A suspended tube sheet comprising an elongated plate having tube-carrying means, a supporting framework, a hanger attached at the top of `the tube sheet to suspend the same from said supporting framework, a vertical flange at the lower end of said plate'and a yoke permanently secured to said framework and having a flange engaging behind said first flange to slidably anchor the lower part of said tube sheet to the framework.

' RALPH M. PARSONS.

. of said last mentioned tube sheets and anchor 

